I think I fixed the Blazer. I checked the wiring on the starter and everything appears to be ok. To rule out the alternator, I disconnected all the wires from it, started the engine and then turned the key off with no luck, the engine kept running. So now, with my trusty $5 DMM in hand I decided to check voltage since the alternator wasn't the culprit.
The first place I checked my voltage was at the fuse box and this is where I found the problem. There are a pair of red wires (one large & one small) in a single connector that plugged into the spot labeled "Ignition Unfused." With the key off I checked that plug and no voltage. With the key on I checked and there was 12+ volts. I also checked the two red wires in case they were feeding the ignition system but they were dead. Before I plugged those two wires back in, I started the engine and then turned the key off and the engine stopped! I plugged the two wires back in and started the engine again but this time it didn't shut off with the key, so I reached under the dash and pulled those two wires out and the engine shut off. That's interesting. There was another spot on the fuse box that wasn't being used, I checked it with the DMM and it had 12+ volts when the key was on and 0 volts when the key was off. I plugged the two red wires into that spot and everything seems to be working like it's supposed to. Go figure? The two red wires have been in the Ignition Unfused spot since I replaced the harness and now three months later it does this. Weird. In case you're wondering, the stock harness had the two red wires plugged into the Ignition Unfused spot also, which is why I plugged the new harness in there. For now everything seems to be working the way it's supposed to. I'm going to keep digging around with the m-m though, maybe I'll find something that shouldn't be. Thanks. Herb
